Motorcycle Tire Sizes
Motorcycle Tire Sizes Explained: MT90, MU85, Metric & Alpha Size Conversion Guide
The quick answer: MT90 is the alphanumeric equivalent of a 130/90 metric motorcycle tire.
What size is an MT90 motorcycle tire?
MT90-16 ≈ 130/90-16
MT90B16 ≈ 130/90B16
If you've been shopping for motorcycle tires — especially for a Harley-Davidson, cruiser, or older motorcycle — you may have noticed sizes that don't look anything like the familiar 120/70-17 or 180/55-17 found on modern sport bikes.
Instead, you might find:
MT90B16 · MU85B16 · MH90-21 · MJ90-19 · MV85B16 · 5.00-16 · 130/90B16
Why are there so many ways to describe what appear to be the same tire sizes?
Motorcycle tires have been labeled using several different sizing systems over the years. Metric sizing is the most common system today, but older alphanumeric and inch-based sizes never completely disappeared. They are still found on many Harley-Davidsons, American cruisers, vintage motorcycles, and replacement tire lines.
Here's how to decode them.
Motorcycle Tire Size Conversion Chart
These are the most common approximate conversions you'll encounter on street motorcycles:
| Alpha Tire Size | Common Metric Equivalent | Approx. Inch Size | Printed For |
|---|---|---|---|
| MH90 | 80/90 Dunlop published chart | 2.50 to 2.75 | Front |
| MJ90 | 90/90 Dunlop published chart | 2.75 to 3.00 | Front |
| MM90 | 100/90 Dunlop published chart | 3.25 to 3.50 | Front |
| MN90 | 110/90 Dunlop published chart | 3.75 to 4.00 | Front |
| MR90 | 120/90 Dunlop published chart | 4.25 to 4.50 | Front |
| MT90 | 130/90 Dunlop published chart | 5.00 to 5.10 | Front |
| MP85 | ≈ 110/90 or 120/80 Dunlop published chart · Motorcycle Tire Center | 4.00 to 4.25 / 4.0 to 4.75 | Rear |
| MR90 | 120/90 Dunlop published chart | 4.50 to 4.75 | Rear |
| MT90 | 130/90 Dunlop published chart | 5.00 to 5.10 | Rear |
| MU90 | 140/90 Dunlop published chart | 5.50 to 6.00 | Rear |
| MV85 | 150/80 or 150/90 Dunlop published chart | 6.00 to 6.25 | Rear |
| MU85 | 140/90 Motorcycle Tire Center | 5.50 to 6.00 | Rear |
| MV90 | ≈ 150/90 Motorcycle Tire Center | 6.00 to 6.25 | Rear |
There can be some overlap between size designations, particularly with older sizes such as MP85, MN90, MM90 and MV85. Manufacturer conversion charts are not always identical.
That's important because a conversion chart should be treated as a size-family reference, not permission to install any tire that appears close enough.
Always verify the tire's actual dimensions, recommended rim width, load rating, speed rating and motorcycle fitment before changing from the manufacturer's specified size.
Metric to alpha
| Common Metric Equivalent | Alpha Equivalent |
|---|---|
| 80/90 | MH90 Front |
| 90/90 | MJ90 Front |
| 100/90 | MM90 Front |
| 110/90 | MN90 Front, MP85 ≈ Rear |
| 120/80 | MP85 ≈ Rear |
| 120/90 | MR90 Front, MR90 Rear |
| 130/90 | MT90 Front, MT90 Rear |
| 140/90 | MU85 Rear, MU90 Rear |
| 150/80 | MV85 Rear |
| 150/90 | MV85 Rear, MV90 ≈ Rear |
Where these numbers come from
Rows marked Dunlop published chart are transcribed from Dunlop's printed motorcycle street tire size conversion chart. Rows marked Motorcycle Tire Center are from our own shop table for codes that chart does not list. Where a source prints two metric sizes for one code, both are shown.
What Does MT90 Mean?
Let's decode one of the most commonly searched motorcycle tire sizes:
MT90B16 74H
Each part tells you something different.
M — Motorcycle
The first letter identifies it as a motorcycle tire designation.
T — Tire width code
In the alphanumeric system, the second letter represents a width category. For an MT tire, that corresponds approximately to a 130 mm metric tire width.
90 — Aspect ratio
Just like modern metric sizing, this represents the height of the tire's sidewall as a percentage of its width. An MT90 is approximately 130 mm wide with a sidewall height around 90% of that width.
B — Bias-belted construction
B indicates a bias-ply tire reinforced with belts beneath the tread. If you see an R, the tire uses radial construction. A dash or the absence of a construction letter generally indicates conventional bias construction, depending on the tire designation.
16 — Rim diameter
The tire fits a 16-inch motorcycle wheel.
74 — Load index
The load index tells you the maximum rated load of the tire under the specified conditions.
H — Speed rating
H is the tire's speed rating. An H-rated motorcycle tire is rated up to 130 mph under its specified load and operating conditions.
Put it together and MT90B16 74H describes a roughly 130/90-size, bias-belted motorcycle tire for a 16-inch wheel, with its associated load and speed rating.
Is MT90 the Same as 130/90?
For tire-size shopping purposes: MT90 ≈ 130/90.
That's why you'll sometimes see manufacturers list a tire as 130/90B16 (MT90B16).
However, don't interpret the word “equivalent” as meaning every MT90 and every 130/90 tire is physically identical.
Two tires carrying equivalent nominal sizes can differ slightly in:
- Actual section width
- Overall diameter
- Tread width
- Tread depth
- Tire profile
- Recommended rim width
- Load capacity
- Construction
- Clearance once installed
Even two tires both labeled 130/90-16 can have slightly different actual dimensions depending on the manufacturer and model.
Think of MT90 and 130/90 as belonging to the same general size class, rather than being guaranteed clones of one another.
What Size Is MT90-16?
MT90-16 is approximately equivalent to 130/90-16.
The 16 does not affect the MT-to-metric conversion. It simply tells you the rim diameter.
For example: MT90-16 → 130/90-16 and MT90B16 → 130/90B16.
An MT90 could theoretically be made for another wheel diameter as well, so always pay attention to the final number.
A 16-inch tire cannot be installed on a 17-, 18-, 19- or 21-inch wheel regardless of the width designation.
What Size Is MU85B16?
Another very common Harley-Davidson size is MU85B16.
This corresponds approximately to the 140/90-16 size class. So as a quick reference: MU85B16 ≈ 140/90B16.
You'll see MU85B16 particularly often on Harley-Davidson rear tires.
The confusing part is the 85. You might reasonably assume that MU85 should translate directly to 140/85 in modern metric notation.
It doesn't necessarily work that way.
Alphanumeric-to-metric sizing is based on established dimensional equivalencies rather than simply replacing the letters with a metric width number. Major tire manufacturers commonly cross-reference MU85 and MU90 with the 140/90 class.
That's one reason you should use a manufacturer's conversion or fitment chart instead of trying to mathematically translate the letters yourself.
What Size Is MH90-21?
MH90 ≈ 80/90. Therefore MH90-21 ≈ 80/90-21.
This is a narrow 21-inch front tire size commonly associated with cruisers, choppers and motorcycles using a tall, narrow front wheel.
The same logic applies to other rim diameters: MH90-19 ≈ 80/90-19 and MH90-21 ≈ 80/90-21.
The MH portion describes the general tire size while the final number describes the wheel diameter.
Common Alpha Motorcycle Tire Sizes
Here's an easier cheat sheet to remember:
- MH90→ 80/90
- MJ90→ 90/90
- MM90→ 100/90
- MN90→ 110/90
- MR90→ 120/90
- MT90→ 130/90
- MP85→ ≈ 110/90 or 120/80
- MU90→ 140/90
- MV85→ 150/80 or 150/90
- MU85→ 140/90
- MV90→ ≈ 150/90
As the second letter moves upward through the alphabet, the tire generally becomes wider.
But don't treat that as a formula for sizes that aren't listed. The alpha system uses defined size classes rather than a simple number-per-letter calculation.
Why Do Motorcycle Tires Have Alpha Sizes at All?
The simple answer is history.
Motorcycle tire sizing developed over decades, and the industry hasn't always used today's metric system.
Older motorcycles may have been designed and documented using inch-based tire sizes such as 3.50-18 or 5.00-16.
Another sizing system used letters to identify the tire's width class, producing sizes such as MH90-21, MT90B16 and MU85B16.
Eventually, the metric format became the dominant way of describing motorcycle tires: 130/90B16, 120/70ZR17, 180/55ZR17.
But motorcycles stay on the road for decades, and manufacturers don't simply erase an established tire designation when a newer sizing convention becomes popular.
There are also huge numbers of Harley-Davidsons and other cruisers originally specified with alphanumeric tire sizes. Tire manufacturers continue producing tires for those applications, so the sizing system survives.
That's why you can walk into a motorcycle tire shop today and encounter a modern tire carrying an old-style MT90B16 designation right next to a tire labeled 130/90B16. Both systems are still valid.
Reading a modern metric size
This guide covers alpha sizes and how they convert. For how to read a modern metric size such as 120/70ZR17 from the sidewall, see our motorcycle tire size guide. Motorcycle tire size guide
Why Doesn't a 130 Tire Measure Exactly 130 mm?
This causes a lot of confusion.
The width printed on a motorcycle tire is a nominal size, not a promise that the inflated tire will measure exactly that number with a tape measure.
Actual tire dimensions depend on the manufacturer, tire model, tread design, casing construction, measuring rim width, actual rim width, air pressure, load and production tolerances.
Mounting the same nominal tire on different approved rim widths can even change its measured width and profile.
That's why replacing a 130 with a 140 isn't simply a matter of asking whether another 10 mm will fit.
Can I Replace a 130/90 With a 140/90?
Sometimes people see MT90 = 130/90 and MU90 = 140/90 and assume moving from MT to MU is an easy way to get a wider tire.
It may fit — but don't assume it will.
A wider tire can affect fender clearance, belt or chain clearance, swingarm clearance, tire profile, steering response, overall diameter, ride height, speedometer accuracy and load characteristics.
The rim also needs to fall within the tire manufacturer's approved rim-width range.
On motorcycles, a tire that physically squeezes into the available space isn't necessarily the correct tire.
If you're trying to change sizes, check the actual specifications rather than relying on the number alone.
What Do Motorcycle Tire Construction Letters Mean?
You may see several variations of the same basic size, for example 130/90-16, 130/90B16 and 130/90R16. They are not necessarily the same tire.
“-” — Bias-Ply
A dash generally identifies conventional diagonal or bias-ply construction.
“B” — Bias-Belted
A B indicates bias-ply construction with additional belt reinforcement. Example: MT90B16.
“R” — Radial
An R indicates radial construction. Example: 180/55R17. You may also see ZR on high-speed radial motorcycle tires.
Do not casually substitute radial and bias tires just because their dimensions are the same. Tire construction is part of the motorcycle's intended fitment.
What Do 73H, 74H and 77H Mean?
The numbers and letters after the tire size are not part of the physical size itself.
For example, in MT90B16 74H, 74 is the load index and H is the speed rating.
Common motorcycle speed symbols include:
| Rating | Maximum Rated Speed |
|---|---|
| J | 62 mph |
| P | 94 mph |
| S | 112 mph |
| H | 130 mph |
| V | 149 mph |
| W | 168 mph |
Load ratings matter just as much as tire dimensions, especially on heavier touring motorcycles carrying a passenger or luggage.
Never replace a tire based only on width and rim diameter while ignoring its required load and speed ratings.
Why Are Alpha Sizes So Common on Harley-Davidsons?
Harley-Davidson is probably the biggest reason American riders continue encountering sizes such as MT90 and MU85.
Various Harley models have used tire specifications such as MT90B16 and MU85B16 alongside conventional metric sizes such as 130/90B16, 150/80B16 and 180/65B16.
Because millions of these motorcycles remain on the road, manufacturers continue producing replacement tires using those original or familiar designations.
So if your Harley owner's manual says MT90B16, seeing a modern replacement tire labeled 130/90B16 doesn't necessarily mean you're looking at the wrong size.
It means you need to determine whether that specific tire is approved as an equivalent fitment.
What About Old Inch Motorcycle Tire Sizes?
Vintage motorcycles can make things even more interesting.
You may find a tire labeled 3.50-18, 4.00-18 or 5.00-16.
Instead of specifying width in millimeters, these older sizes describe nominal tire width in inches.
Approximate cross-references include:
| Approx. Inch Size | Common Metric Equivalent |
|---|---|
| 2.50 to 2.75 | 80/90 |
| 2.75 to 3.00 | 90/90 |
| 3.25 to 3.50 | 100/90 |
| 3.75 to 4.00 | 110/90 |
| 4.00 to 4.25 | 110/90 |
| 4.0 to 4.75 | 110/90 / 120/80 |
| 4.25 to 4.50 | 120/90 |
| 4.50 to 4.75 | 120/90 |
| 5.00 to 5.10 | 130/90 |
| 5.50 to 6.00 | 140/90 |
| 6.00 to 6.25 | 150/80 / 150/90 |
Again, these are conversion ranges, not guaranteed physical equivalents.
Vintage fitment deserves extra attention because changing overall tire diameter can alter chassis geometry and because older rims may have different construction or tube requirements.
Motorcycle Tire Sizes Are Not Exact Conversions
This is the most important thing to remember from this guide.
A chart might say MT90 = 130/90. That's correct as a general conversion.
But that doesn't mean every MT90 tire is dimensionally identical to every 130/90 tire.
Think of the conversion more like translating between two sizing languages. You're identifying the same general tire size category. You still need to check the specific tire.
The same applies when converting between alpha and metric sizes, inch and metric sizes, bias and radial tires, different brands and different tire models.
When clearance is tight, a few millimeters can matter.
Quick Motorcycle Tire Size Reference
If you just came here looking for an answer, here are the common ones:
- What size is MT90?
- MT90 is approximately 130/90.
- What is MT90-16 equivalent to?
- Approximately 130/90-16.
- What is MT90B16 equivalent to?
- Approximately 130/90B16.
- What size is MU85B16?
- Approximately the 140/90B16 size class.
- What size is MU90?
- Approximately 140/90.
- What size is MH90?
- Approximately 80/90.
- What is MH90-21?
- Approximately 80/90-21.
- What size is MJ90?
- Approximately 90/90.
- What size is MR90?
- Approximately 120/90.
- What does B mean in MT90B16?
- Bias-belted tire construction.
- What does 16 mean in MT90B16?
- It fits a 16-inch wheel.
Tires we carry in these sizes
Every tire below is a size class from the chart above. Prices and stock are confirmed on each tire's own page.
Michelin's long-reigning cruiser benchmark — built for heavyweight baggers, loaded two-up touring, and all-weather confidence across every mile.
Michelin's long-reigning cruiser benchmark — built for heavyweight baggers, loaded two-up touring, and all-weather confidence across every mile.
The Commander II is the go-to choice for heavyweight cruiser and touring riders who want maximum mileage, confident wet-weather traction, and proven reliability over the long haul.
Michelin's flagship cruiser tire built for V-twin riders who ride in all weather — serious mileage, serious wet grip, zero compromises on confidence.
Michelin's flagship cruiser tire built for V-twin riders who ride in all weather — serious mileage, serious wet grip, zero compromises on confidence.
Best fit for V-twin riders who log real miles in unpredictable weather and want maximum wet-road confidence without giving up tread life
A dependable bias-ply cruiser tire built for metric and Japanese platforms — the OE-trusted choice for Shadow, V-Star, and Vulcan riders who want mileage and comfort over track credentials.
A dependable bias-ply cruiser tire built for metric and Japanese platforms — the OE-trusted choice for Shadow, V-Star, and Vulcan riders who want mileage and comfort over track credentials.
The D404 is the go-to replacement tire for metric cruiser riders who want honest mileage and predictable street manners without paying for performance they'll never use.
Metzeler's premium long-haul tire built for custom baggers and touring rigs that eat miles without sacrificing predictable handling.
Metzeler's premium long-haul tire built for custom baggers and touring rigs that eat miles without sacrificing predictable handling.
The ME 888 Marathon Ultra is the go-to tire for serious touring and bagger riders who want maximum mileage with dependable, consistent handling from day one to replacement day.
Dunlop's heavy-duty touring tire built for Gold Wing mileage, all-weather grip, and the long haul — not the canyon sprint.
Dunlop's heavy-duty touring tire built for Gold Wing mileage, all-weather grip, and the long haul — not the canyon sprint.
Best suited for high-mileage Gold Wing and cruiser riders who need dependable all-weather grip and long replacement intervals over sport performance.
Michelin's factory-spec cruiser tire built exclusively for Harley-Davidson — OE performance with all-weather confidence for the miles-hungry rider.
Michelin's factory-spec cruiser tire built exclusively for Harley-Davidson — OE performance with all-weather confidence for the miles-hungry rider.
The Scorcher 31 is the benchmark street tire for Harley-Davidson riders who demand long-lasting, all-weather grip without giving up street feel.
Michelin's flagship V-twin touring tire — built for loaded baggers, long miles, and all-weather confidence on every road in between.
Michelin's flagship V-twin touring tire — built for loaded baggers, long miles, and all-weather confidence on every road in between.
The Commander III is the go-to choice for V-twin touring riders who demand maximum mileage and all-weather reliability over weekend sport performance.
Michelin's first radial knobby — built for adventure riders who split time between asphalt and dirt without wanting to compromise on either.
Michelin's first radial knobby — built for adventure riders who split time between asphalt and dirt without wanting to compromise on either.
Best suited for adventure riders who log real mixed-surface miles — strong on dirt and fully capable on pavement, with honest mileage trade-offs for the capability it delivers.
MH90 · 80/90-10 · MH90 · 80/90-14 · MH90 · 80/90-16 · MH90 · 80/90-17 · MH90 · 80/90-18 · MH90 · 80/90-21 · MJ90 · 90/90-10 · MJ90 · 90/90-12 · MJ90 · 90/90-14 · MJ90 · 90/90-16 · MJ90 · 90/90-17 · MJ90 · 90/90-18 · MJ90 · 90/90-19 · MJ90 · 90/90-21 · MM90 · 100/90-10 · MM90 · 100/90-12 · MM90 · 100/90-14 · MM90 · 100/90-16 · MM90 · 100/90-17 · MM90 · 100/90-18 · MM90 · 100/90-19 · MN90 / MP85 · 110/90-10 · MN90 / MP85 · 110/90-12 · MN90 / MP85 · 110/90-13 · MN90 / MP85 · 110/90-16 · MN90 / MP85 · 110/90-17 · MN90 / MP85 · 110/90-18 · MN90 / MP85 · 110/90-19 · MP85 · 120/80-12 · MP85 · 120/80-14 · MP85 · 120/80-16 · MP85 · 120/80-17 · MP85 · 120/80-18 · MP85 · 120/80-19 · MR90 · 120/90-10 · MR90 · 120/90-16 · MR90 · 120/90-17 · MR90 · 120/90-18 · MR90 · 120/90-19 · MT90 · 130/90-10 · MT90 · 130/90-15 · MT90 · 130/90-16 · MT90 · 130/90-17 · MT90 · 130/90-18 · MU90 / MU85 · 140/90-10 · MU90 / MU85 · 140/90-15 · MU90 / MU85 · 140/90-16 · MV85 · 150/80-15 · MV85 · 150/80-16 · MV85 · 150/80-17 · MV85 / MV90 · 150/90-15
Frequently Asked Questions
- Is an MT90 tire a 130 tire?
- Yes. An MT90 is generally equivalent to the 130/90 metric size class. An MT90-16 therefore corresponds approximately to a 130/90-16.
- Is MT90B16 exactly the same as 130/90B16?
- They are commonly considered equivalent size designations, but actual tire dimensions, load ratings and construction specifications can vary between tire models. Check the specific manufacturer's specifications before substituting tires.
- What is the difference between MT90 and MU85?
- The biggest difference is width class. MT90 is approximately 130/90 and MU85 is approximately 140/90, so the MU tire is generally the wider size.
- What is an MU85B16 tire in metric size?
- MU85B16 corresponds approximately to the 140/90B16 size class.
- Why does my Harley use MT90 instead of 130/90?
- Harley-Davidson and American cruiser applications continued using the older alphanumeric sizing system even after metric sizing became dominant. Tire manufacturers still make tires using these designations because many motorcycles were originally specified that way.
- What does the M stand for in MT90?
- The M identifies the alphanumeric designation as a motorcycle tire size. The following letter is the width code.
- Does the 90 in MT90 mean 90 mm?
- No. The 90 is the aspect ratio, not the width. MT identifies the tire's width class, which is approximately 130 mm. The 90 indicates a sidewall height approximately 90% of the tire's nominal width.
- Can I replace MT90-16 with 130/90-16?
- Often, yes — they represent the same general size class. But verify the specific replacement tire's approved application, construction, rim width, load index, speed rating and actual dimensions before installing it.
- Can I replace an MT90 with an MU85 to get a wider tire?
- Not automatically. MU85 is a wider size class, and clearance around the fender, swingarm, belt or chain needs to be checked. The wheel must also be approved for the wider tire.
- How do I know what motorcycle tire size I need?
- The safest starting point is the motorcycle manufacturer's specified tire size. You can usually find it in the owner's manual, service information or on the tire currently installed. If you're dealing with a custom motorcycle, aftermarket wheels or an older bike where the original tire size is obsolete, actual rim dimensions and available clearance may need to be checked.